Optimal Plot Dimensions for Performance Testing of Hybrid Potato in the Field

Field trials to evaluate the performance of new varieties are an essential component of potato breeding. Besides the genetic differences, environmental factors can lead to variation in a trial. In variety trials, the observed differences amongst varieties should reflect genetic differences, without a large impact of the random or systematic variation in the field. One way to reduce within-field variation is to adjust the plot size and its shape in a trial. Two years of field trials in which individual plants in 90-plant plots of both diploid hybrid and tetraploid varieties were measured provided data to derive relationships between LSD% and plot size and shape. We provide a method to estimate the equations to calculate the expected variation when using different plot dimensions in a relatively homogeneous trial field for tuber yield, tuber volume, tuber count, tuber shape and the standard deviations of tuber volume and shape. Compared with the yield traits, the variation for tuber shape was relatively small. The effect of plot shape was minor. With these equations, breeders can determine what plot dimensions are needed to reach the desired precision for each trait.

Linkage and QTL mapping for tuber shape and specific gravity in a tetraploid mapping population of potato representing the russet market class

Background Tuber shape and specific gravity (dry matter) are important agronomic traits in potato processing and impact production costs, quality, and consistency of the final processed food products such as French fries and potato chips. In this study, linkage and QTL mapping were performed for these two traits to allow for the implementation of marker-assisted selection to facilitate breeding efforts in the russet market class. Two parents, Rio Grande Russet (female) and Premier Russet (male) and their 205 F1 progenies were initially phenotyped for tuber shape and specific gravity in field trials conducted in Idaho and North Carolina in 2010 and 2011, with specific gravity also being measured in Minnesota in 2011. Progenies and parents were previously genotyped using the Illumina SolCAP Infinium 8303 Potato SNP array, with ClusterCall and MAPpoly (R-packages) subsequently used for autotetraploid SNP calling and linkage mapping in this study. The 12 complete linkage groups and phenotypic data were then imported into QTLpoly, an R-package designed for polyploid QTL analyses. Results Significant QTL for tuber shape were detected on chromosomes 4, 7, and 10, with heritability estimates ranging from 0.09 to 0.36. Significant tuber shape QTL on chromosomes 4 and 7 were specific to Idaho and North Carolina environments, respectively, whereas the QTL on chromosome 10 was significant regardless of growing environment. Single marker analyses identified alleles in the parents associated with QTL on chromosomes 4, 7, and 10 that contributed to significant differences in tuber shape among progenies. Significant QTL were also identified for specific gravity on chromosomes 1 and 5 with heritability ranging from 0.12 to 0.21 and were reflected across environments. Conclusion Fully automated linkage mapping and QTL analysis were conducted to identify significant QTL for tuber shape and dry matter in a tetraploid mapping population representing the russet market class. The findings are important for the development of molecular markers useful to potato breeders for marker-assisted selection for the long tuber shape and acceptable dry matter required by the potato industry within this important market class.

Potato Tuber Shape Phenotyping Using RGB Imaging

Potato tuber shape is an important quality trait for breeding and variety development. Length to width (L/W) ratio is a commonly used method to score potato tubers for suitability for different markets and is relatively easy to measure, though labor intensive when done manually. L/W also does not adequately capture secondary growth and other tuber malformations that contribute to tuber shape. Tuber shape has a genetic component and is a prime target for early breeding selection. In the current study we developed an image analysis pipeline to extract tuber shape statistics from images taken using inexpensive, commercially available cameras. The image processing pipeline was used to evaluate greenhouse grown tubers from 32 unique crosses. Tubers from greenhouse grown plants were then grown in a field located in Vauxhall, AB, Canada, and evaluated for tuber shape. Randomly selected tuber images were also shown to industry agronomists and potato growers located in Southern Alberta and their shape scored for suitability for processing (French fry and chipping) markets. Based on measurements taken from greenhouse grown tubers we were able to classify whether mean tuber shape from field grown plants were within ideal shape parameters for processing markets with ~76–86% accuracy. Based on performance of progeny we identified parents which show higher breeding value for tuber shape.

Exploration and Characterization of “Uwi” Plant (Dioscorea sp.) in East Java Uplands, Indonesia

“Uwi” (Dioscorea sp.) is a tuber plant species with potentials to support the national food diversity program because it has high tolerance when planted in upland areas, which are wide in Indonesia and beyond. The study aims to rescue germplasm of “Uwi” plants through exploration, identification, and collection for the sake of national long–term goal of providing alternative food sources to support food security. The research began with exploration of the west upland area of East Java, and continued with specimen planting for characterization testing in the following year. Exploration resulted in 127 samples of variants observed throughout uplands in Madiun, Ponorogo, Ngawi, Magetan and Pacitan, East Java, Indonesia with each result of 28, 26, 9, 20 and 44 variants. Five big groups of Dioscorea family namely Dioscorea alata, Dioscorea aculeata, Dioscorea hispida, Dioscorea pentaphylla and Dioscorea bulbifera were mapped out as a result. Using SPSS cluster analysis, D. alata as the most variant were specified into 20 groups and further gathered into seven clusters based on its main botanical characteristics of leaf shape, leaf color, stem color, tuber color, tuber shape, and skin color of the tuber. Meanwhile, D. aculeata and D. pentaphylla were each detailed into two sub–clusters and other types were each detailed into one.

Screening and Evaluation of Initial Clonal Generations of Potato Hybrids for Yield and Yield Attributing Characters

A field experiment was conducted during Rabi 2015-16 and 2016-17 at ICAR-Central Potato Research Station, Patna Bihar. In this experiment F1 with initial clonal generations viz F1C1, F1C2 and F1C3 were evaluated. The screening and selection of these generations were done in randomized block design for the character like early bulking, tuber size, tuber shape, depth of eye, tuber colour and resistance to late blight of potato etc. A total of 12,360 True Potato Seeds of 17 successful crosses and 7,322 True Potato Seeds of 23 successful crosses were sown and seedlings were transplanted, out of these 610 and 187 clones were selected during 2015-16 and 2016-17 respectively. Large number of potato cultures were planted for further evaluation in next generations. In F1C3 the cultures were planted along with more than six check varieties of potato. Cultures were evaluated and selected considering total tuber yield, shape, colour and disease reactions for further evaluation in PYT.

Наследование формы клубней в гибридных популяциях картофеля различного генетического происхождения

Цель работы: изучение характера наследования формы клубней в гибридных популяциях картофеля от скрещивания специально подобранных родительских форм, охватывающих широкий ряд изменчивости этого морфологического признака. Материал исследований: селекционные сорта, различающиеся формой клубня от округлой до удлиненной и гибридные популяции от скрещивания по диаллельной схеме. Исследования проводили в 2017-2018 годах на экспериментальных базах ВНИИКХ Коренево и Пышлицы Московской области. В результате изучения характера наследования формы клубней 35 гибридных популяций, полученных от диаллельных скрещиваний родительских компонентов, характеризующихся значительным различием данного признака, установлена широкая вариабельность формы клубней как у селекционных сортов (7,8-16,8), так и гибридного потомства (10,5-22,2) картофеля. В гибридном потомстве изученных родительских форм отмечено расщепление по признаку формы клубней с преобладанием удлиненных клубней и увеличение вариабельности признака по отдельным популяциям. Корреляционная связь индексов формы клубней исходных родительских форм и их потомства варьировала от слабоположительной до слабоотрицательной, что указывает на полигенное контролирование этого признака. Установлена отрицательная корреляция между формой клубней двух материнских форм с удлиненными клубнями и формой клубней их гибридного потомства, уровень которой составляет -0,17 и -0,60 соответственно. В гибридных популяциях с участием материнских форм с удлиненными клубнями под влиянием опылителей с округло-овальными клубнями формировались генотипы с овальными клубнями. Лучшим опылителем, хорошо передающим форму клубней потомству, оказался сорт ВР 808, средний коэффициент наследуемости признака у которого составил 0,36. Остальные отцовские формы по мере снижения коэффициента наследуемости ранжированы в следующем порядке: Голубка (0,33), Инноватор (0,24), Вымпел (0,12), Крепыш (0,01). Среди материнских форм выделились только сорта Ноктюрн (0,29) и Винета (0,29). Использование в скрещиваниях сортов-опылителей, отличающихся повышенным коэффициентом наследуемости формы клубней, позволяет с большей долей вероятности передавать этот признак гибридному потомству.The aim of the work is to study the nature of inheritance of tubers in hybrid potato populations from crossing specially selected parent forms, covering a wide range of variability of this morphological feature. Research material: breeding varieties that differ in tuber shape from rounded to elongated and hybrid populations from crossing according to the diallel scheme. The research was conducted in 2017-2018 at the experimental bases of VNIIKH Korenevo and Pyshlitsy in the Moscow region. As a result of studying the nature of the inheritance of tubers in 35 hybrid populations obtained from diallel crosses of parent components characterized by a significant difference in this characteristic, a wide variability in the shape of tubers was established in both breeding varieties (7.8-16.8) and hybrid offspring (10.5-22.2) of potatoes. In the hybrid offspring of the studied parent forms, there was a cleavage based on the shape of tubers with a predominance of elongated tubers and an increase in the variability of the trait for individual populations. The correlation between the tuber shape indices of the original parent forms and their offspring varied from weakly positive to weakly negative, indicating polygenic control of this trait. A negative correlation was established between the tuber shape of two maternal forms with elongated tubers and the tuber shape of their hybrid offspring, the level of which is -0.17 and -0.60, respectively. In hybrid populations with the participation of mother forms with elongated tubers, genotypes with oval tubers are formed under the influence of round-oval pollinators. The best pollinator, well transmitting the shape of tubers to offspring, was the variety BP 808, which had an average heritability coefficient of 0.36. The rest of the paternal forms are ranked in the following order according to the number of decrease in the heritability coefficient: Golubka (0.33), Innovator (0.24), Vimpel (0.12), Krepish (0.01). Only Nocturne (0.29) and Vineta (0.29) varieties were distinguished among the mother forms. The use of pollinator varieties in crosses that differ in an increased heritability coefficient of the tuber shape makes it possible to pass this trait to hybrid offspring with a greater probability.

Begonia ehuangzhangensis (sect. Diploclinium, Begoniaceae), a new species from Guangdong, China

A new species, Begonia ehuangzhangensis, from Yangchun City, Guangdong Province, China, is described and illustrated. Morphologically, B. ehuangzhangensis is most similar to B. fimbristipula in tuber shape, leaf number, and placentation type but significantly differs by indumentum characters of petiole and blade, tepal number of male flower, flower size, capsule size, and flowering period. Begonia ehuangzhangensis also resembles B. rongjiangensis in plant shape, number of tepals, placentation type, and flowering period, differing by indumentum characters of ovary, bract and outer tepals of male flower, flower size, shape of stigmas, leaf number, and leaf margin.