The importance of coconut seedling production in guyana

The demand for coconut water and coconut oil is increasing thus there is interest in expanding coconut cultivation. Coconut is primarily planted on approximately 28,500 acres by more than 1,400 farmers along the Guyana coastline with the Atlantic Ocean and in the Pomeroon Riverain area. Tall types (e.g. Jamaica Tall) are planted for oil while Dwarf types (e.g. Malaysian Dwarf Green, Suriname Brown) are planted primarily for water. At least 50% of the Tall type population is more than 50 years old and needs to be replanted to increase productivity. Farmers traditionally collect seedlings growing from dropped nuts at the base of trees without attention to prolificacy. Since a coconut tree productive life is more than 50 years, the economic impact of this practice can be significant. Via training programs, CARDI is encouraging the structured production of coconut seedlings to increase yields. This project aims to enhance the supply of quality seedlings using local seed nuts. Mother palms that display prolific bearing habits, resistance to pest and diseases plus vigorous growth habit were geotagged and recorded in a database. Seed nuts were purchased from farmers who own these trees and subsequently distributed (in batches of 400) to ten selected (age, gender, location) lead farmers to establish coconut seedling nurseries. Each lead farmer was assisted by 10 second ring farmers in the establishment of their nurseries under CARDI supervision. Results to date show that weed control and irrigation were important nursery activities. Some nurseries needed to be fenced to counter damage by animals (cows, sheep, goats). Average germination of seed nuts was approximately 50%. Available seedlings are being distributed to second ring farmers and lead farmers. CARDI will continue the national survey to identify outstanding mother palms. Measures to increase average germination must also be implemented. Local coconut seedling nurseries should therefore be encouraged as their “success” will alleviate the pressure to import seed nuts thus avoiding the attendant risk of introducing exotic diseases (e.g. lethal yellowing disease) into Guyana. Further, given that a coconut palm will live 50 to 70 years, the importance of carefully selecting premium quality coconut seedlings as a bedrock to develop and grow the industry cannot be over emphasized.

Ascomycetes from the relic forest of Oreomunnea mexicana, Oaxaca, Mexico

La Esperanza is an Oaxacan relic area of the Tertiary, dominated by the big tree Oreomunnea mexicana (Juglandaceae). The forest is part of the priority region for the conservation of La Chinantla and constitutes one of the most conserved Mexican tropical montane cloud forests. We studied the Ascomycetes fungi and found 63 species, of which 32 are new records for Oaxaca. Ascocoryne inflata, Calyculosphaeria macrospora, Cercophora costaricensis, Chaetosphaeria ellisii, Coccomyces limitatus, Lasiosphaeria ovina, Leptogidium dendriscum, Marthamyces quadrifidus, Stereocaulon didymicum and Thelonectria lucida are new records for Mexico. Xylaria was the most diverse genus with 12 species. The most abundant species were Xylaria arbuscula and Lachnum apalum. The main growth habit was lignicolous. The tropical montane cloud forest of La Esperanza has unique characteristics allowing great taxonomic diversity of Ascomycetes.

DIONYSIA SPLENDENS (PRIMULACEAE), A NEW SPECIES FROM THE FARS PROVINCE OF IRAN

Dionysia splendens Alipour, Mehregan & Lidén, sp. nov., from Fars, Iran, is a unique species that cannot be easily accommodated in any hitherto recognised section of the genus and is immediately recognised by its large flowers and pectinate leaves with very broad pale and thick midvein. It agrees with Dionysia cespitosa Duby (Boiss.) in the small flat leaves, stalked inflorescence with large bracts, and few large ellipsoid seeds, but differs in the tubular calyx and large purplish-blue corolla. It is also somewhat reminiscent of Dionysia viva Lidén & Zetterl. in growth habit and inflorescence structure, but that species has large irregularly dentate leaves, yellow corolla and numerous small angular seeds. Dionysia splendens is so far known from a single locality with c.200 mature individuals. An updated key to Dionysia species in the Zagros mountains is provided.

A novel locus (Bnsdt2) in a TFL1 homologue sustaining determinate growth in Brassica napus

Background The determinate growth habits is beneficial for plant architecture modification and the development of crops cultivars suited to mechanized production systems. Which play an important role in the genetic improvement of crops. In Brassica napus, a determinate inflorescence strain (4769) has been discovered among doubled haploid (DH) lines obtained from a spring B. napus × winter B. napus cross, but there are few reports on it. We fine mapped a determinate inflorescence locus, and evaluated the effect of the determinate growth habit on agronomic traits. Results In this study, we assessed the effect of the determinate growth habit on agronomic traits. The results showed that determinacy is beneficial for reducing plant height and flowering time, advancing maturity, enhancing lodging resistance, increasing plant branches and maintaining productivity. Genetic analysis in the determinate (4769) and indeterminate (2982) genotypes revealed that two independently inherited recessive genes (Bnsdt1, Bnsdt2) are responsible for this determinate growth trait. Bnsdt2 was subsequently mapped in BC2 and BC3 populations derived from the combination 2982 × 4769. Bnsdt2 could be delimited to an approximately 122.9 kb region between 68,586.2 kb and 68,709.1 kb on C09. BLAST analysis of these candidate intervals showed that chrC09g006434 (BnaC09.TFL1) is homologous to TFL1 of A. thaliana. Sequence analysis of two alleles identified two non-synonymous SNPs (T136C, G141C) in the first exon of BnaC09.TFL1, resulting in two amino acid substitutions (Phe46Leu, Leu47Phe). Subsequently, qRT-PCR revealed that BnaC09.TFL1 expression in shoot apexes was significantly higher in NIL-4769 than in 4769, suggesting its essential role in sustaining the indeterminate growth habit. Conclusions In this study, the novel locus Bnsdt2, a recessive genes for determinate inflorescence in B. napus, was fine-mapped to a 68,586.2 kb - 68,709.1 kb interval on C09. The annotated genes chrC09g006434 (BnaC09.TFL1) that may be responsible for inflorescence traits were found.

Inheritance of growth habit under photoperiod insensitive genetic background in dolichos bean (Lablab purpureus (L.) Sweet)

Development of high yielding cultivars with determinate growth habit in photoperiod insensitive (PIS) background is one of the major objectives of breeding grain legumes crops including dolichos bean. A thoroughly validated genetic basis is a prerequisite for breeding dolichos bean for determinate growth habit in PIS background. Based on the published reports by researchers of our laboratory and those by others, and our unpublished data, we hypothesized that the number and mode of action of genes controlling growth habit differ with degree of photoperiod sensitivity of the genetic material used to investigate the inheritance of growth habit in dolichos bean. To test this hypothesis, we compared the number and mode of action of genes controlling growth habit between segregating generations in Photoperiod sensitive (PS) and those in PIS genetic backgrounds. While indeterminate and determinate plants segregated in 15:1 ratio in F2 populations derived from crosses between determinate PIS and indeterminate PIS parents, they segregated in 9:7 ratio with indeterminacy being dominant in F2 populations derived from crosses between determinate PIS and indeterminate PS parents. These patterns of segregation (15:1 and 9:7) in favour of indeterminate and determinate plants, respectively in F2 populations were confirmed in F3 populations of PIS and PS genetic backgrounds based on good fit between observed and expected ratios (55:9 and 29:35, respectively) in favour of indeterminate and determinate plants, respectively. The patterns of segregation in F2 populations were further confirmed in F3 populations based on good fit between observed and expected ratios of 3:1 segregating and non-segregating families, and of 3:1 indeterminate and determinate non-segregating families, respectively.

The Relationships between Plant Developmental Traits and Winter Field Survival in Rye (Secale cereale L.)

Overwintering cereals accumulate low temperature tolerance (LTT) during cold acclimation in the autumn. Simultaneously, the plants adjust to the colder season by making developmental changes at the shoot apical meristem. These processes lead to higher winter hardiness in winter rye varieties (Secale cereale L.) adapted to Northern latitudes as compared to other cereal crops. To dissect the winter-hardiness trait in rye, a panel of 96 genotypes of different origins and growth habits was assessed for winter field survival (WFS), LTT, and six developmental traits. Best Linear Unbiased Estimates for WFS determined from five field trials correlated strongly with LTT (r = 0.90, p < 0.001); thus, cold acclimation efficiency was the major contributor to WFS. WFS also correlated strongly (p < 0.001) with final leaf number (r = 0.80), prostrate growth habit (r = 0.61), plant height (r = 0.34), but showed weaker associations with top internode length (r = 0.30, p < 0.01) and days to anthesis (r = 0.25, p < 0.05). The heritability estimates (h2) for WFS-associated traits ranged from 0.45 (prostrate growth habit) to 0.81 (final leaf number) and were overall higher than for WFS (h2 = 0.48). All developmental traits associated with WFS and LTT are postulated to be regulated by phytohormone levels at shoot apical meristem.

Unraveling genetics of semi-determinacy and identification of markers for indeterminate stem growth habit in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is predominantly an indeterminate plant and tends to generate vegetative growth when the ambient is conducive for soil moisture, temperature and certain other environmental conditions. The semi-determinate (SDT) types are comparatively early, resistant to lodging and found to be similar in their yield potential to indeterminate (IDT) lines. Indeterminate and semi-determinate genotypes are found to be similar during early stage, which makes it difficult to distinguish between them. Thus, there is a need to identify molecular markers linked either to indeterminate or semi-determinate plant types. The present study was carried out to study the genetics of semi-determinacy and identify molecular markers linked to stem growth habit. The study was undertaken in the cross involving BG 362(IDT) × BG 3078-1(SDT). All F1 plants were indeterminate, which indicates that indeterminate stem type is dominant over semi-determinate. In further advancement to F2 generation, F2 plants are segregated in the ratio of 3(Indeterminate): 1(Semi-determinate) that indicates that the IDT and SDT parents which are involved in the cross differed for a single gene. The segregation pattern observed in F2 is confirmed in F3 generation. The parental polymorphic survey was undertaken for molecular analysis using total of 245 SSR markers, out of which 41 polymorphic markers were found to distinguish the parents and were utilized for bulked segregant analysis (BSA). The segregation pattern in F2 indicates that the IDT (Indeterminate) and SDT (Semi-determinate) parents which are involved in the cross differed for single gene. The segregation pattern of F2 and F3 derived from the cross BG 362 (IDT) × BG 3078-1 (SDT) confirmed the genotypic structure of the newly found SDT genotype BG 3078-1 as dt1dt1Dt2Dt2. Three SSR markers TA42, Ca_GPSSR00560 and H3DO5 were found to be putatively linked to Dt1 locus regulating IDT stem growth habit. Our results indicate that the SSR markers identified for Dt1 locus helps to differentiate stem growth habit of chickpea in its early growth stage itself and can be efficiently utilized in Marker Assisted Selection (MAS) for changed plant type in chickpea.