Plant Breeding and Management Strategies to Minimize the Impact of Water Scarcity and Biotic Stress in Cereal Crops under Mediterranean Conditions

Wheat and rice are two main staple food crops that may suffer from yield losses due to drought episodes that are increasingly impacted by climate change, in addition to new epidemic outbreaks. Sustainable intensification of production will rely on several strategies, such as efficient use of water and variety improvement. This review updates the latest findings regarding complementary approaches in agronomy, genetics, and phenomics to cope with climate change challenges. The agronomic approach focuses on a case study examining alternative rice water management practices, with their impact on greenhouse gas emissions and biodiversity for ecosystem services. The genetic approach reviews in depth the latest technologies to achieve fungal disease resistance, as well as the use of landraces to increase the genetic diversity of new varieties. The phenomics approach explores recent advances in high-throughput remote sensing technologies useful in detecting both biotic and abiotic stress effects on breeding programs. The complementary nature of all these technologies indicates that only interdisciplinary work will ensure significant steps towards a more sustainable agriculture under future climate change scenarios.

Raise and characterization of a bread wheat hybrid line (Tulaykovskaya 10 × Saratovskaya 29) with chromosome 6Agi2 introgressed from Thinopyrum intermedium

Wheatgrass Thinopyrum intermedium is a source of agronomically valuable traits for common wheat. Partial wheat–wheatgrass amphidiploids and lines with wheatgrass chromosome substitutions are extensively used as intermediates in breeding programs. Line Agis 1 (6Agi2/6D) is present in the cultivar Tulaykovskaya 10 pedigree. Wheatgrass chromosome 6Agi2 carries multiple resistance to fungal diseases in various ecogeographical zones. In this work, we studied the transfer of chromosome 6Agi2 in hybrid populations Saratovskaya 29×Tulaykovskaya 10 (S29×T10) and Tulaykovskaya 10×Saratovskaya 29 (T10×S29). Chromosome 6Agi2 was identified by PCR with chromosome-specific primers and by genomic in situ hybridization (GISH). According to molecular data, 6Agi2 was transmitted to nearly half of the plants tested in the F2 and F3 generations. A new breeding line 49-14 (2n = 42) with chromosome pair 6Agi2 was isolated and characterized in T10×S29 F5 by GISH. According to the results of our field experiment in 2020, the line had high productivity traits. The grain weights per plant (10.04±0.93 g) and the number of grains per plant (259.36±22.49) did not differ significantly from the parent varieties. The number of grains per spikelet in the main spike was significantly higher than in S29 (p ≤ 0.001) or T10 (p ≤ 0.05). Plants were characterized by the ability to set 3.77±0.1 grains per spikelet, and this trait varied among individuals from 2.93 to 4.62. The grain protein content was 17.91 %, and the gluten content, 40.55 %. According to the screening for fungal disease resistance carried out in the field in 2018 and 2020, chromosome 6Agi2 makes plants retain immunity to the West Siberian population of brown rust and to dominant races of stem rust. It also provides medium resistant and medium susceptible types of response to yellow rust. The possibility of using lines/varieties of bread wheat with wheatgrass chromosomes 6Agi2 in breeding in order to increase protein content in the grain, to confer resistance to leaf diseases on plants and to create multiflowered forms is discussed.

Two pathogenesis-related proteins interact with leucine-rich repeat proteins to promote Alternaria leaf spot resistance in apple

Alternaria leaf spot in apple (Malus x domestica), caused by the fungal pathogen Alternaria alternata f. sp. mali (also called A. mali), is a devastating disease resulting in substantial economic losses. We previously established that the resistance (R) protein MdRNL2, containing a coiled-coil, nucleotide-binding, and leucine-rich repeat (CCR-NB-LRR) domain, interacts with another CCR-NB-LRR protein, MdRNL6, to form a MdRNL2–MdRNL6 complex that confers resistance to A. mali. Here, to investigate the function of the MdRNL2–MdRNL6 complex, we identified two novel pathogenesis-related (PR) proteins, MdPR10-1 and MdPR10-2, that interact with MdRNL2. Yeast two-hybrid (Y2H) assays and bimolecular fluorescence complementation (BiFC) assays confirmed that MdPR10-1 and MdPR10-2 interact with MdRNL2 and MdRNL6 at the leucine-rich repeat domain. Transient expression assays demonstrated that accumulation of MdPR10-1 and MdPR10-2 enhanced the resistance of apple to four strains of A. mali that we tested: ALT1, GBYB2, BXSB5, and BXSB7. In vitro antifungal activity assays demonstrated that both the proteins contribute to Alternaria leaf spot resistance by inhibiting fungal growth. Our data provide evidence for a novel regulatory mechanism in which MdRNL2 and MdRNL6 interact with MdPR10-1 and MdPR10-2 to inhibit fungal growth, thereby contributing to Alternaria leaf spot resistance in apple. The identification of these two novel PR proteins will facilitate breeding for fungal disease resistance in apple.

Recent Progress in Enhancing Fungal Disease Resistance in Ornamental Plants

Fungal diseases pose a major threat to ornamental plants, with an increasing percentage of pathogen-driven host losses. In ornamental plants, management of the majority of fungal diseases primarily depends upon chemical control methods that are often non-specific. Host basal resistance, which is deficient in many ornamental plants, plays a key role in combating diseases. Despite their economic importance, conventional and molecular breeding approaches in ornamental plants to facilitate disease resistance are lagging, and this is predominantly due to their complex genomes, limited availability of gene pools, and degree of heterozygosity. Although genetic engineering in ornamental plants offers feasible methods to overcome the intrinsic barriers of classical breeding, achievements have mainly been reported only in regard to the modification of floral attributes in ornamentals. The unavailability of transformation protocols and candidate gene resources for several ornamental crops presents an obstacle for tackling the functional studies on disease resistance. Recently, multiomics technologies, in combination with genome editing tools, have provided shortcuts to examine the molecular and genetic regulatory mechanisms underlying fungal disease resistance, ultimately leading to the subsequent advances in the development of novel cultivars with desired fungal disease-resistant traits, in ornamental crops. Although fungal diseases constitute the majority of ornamental plant diseases, a comprehensive overview of this highly important fungal disease resistance seems to be insufficient in the field of ornamental horticulture. Hence, in this review, we highlight the representative mechanisms of the fungal infection-related resistance to pathogens in plants, with a focus on ornamental crops. Recent progress in molecular breeding, genetic engineering strategies, and RNAi technologies, such as HIGS and SIGS for the enhancement of fungal disease resistance in various important ornamental crops, is also described.

A study of the genetic diversity in the world soybean collection using microsatellite markers associated with fungal disease resistance

Background. Soybean (Glycine max (L.) Merr.) gradually becomes one of the leading legume crops in Kazakhstan. The area under soybeans in the country has been increasing annually and requires the development of adapted cultivars with a higher yield, improved quality characters, and resistance to emerging fungal diseases. The enlargement of the crop’s gene pool also suggests the need to study and document local soybean accessions to meet the standards of the available world soybean collection by using reliable and informative types of DNA markers.Materials and methods. In this study, the soybean collection consisting of 288 accessions from different countries, including 36 cultivars and promising lines from Kazakhstan, was studied. The molecular genetic analysis was performed using nine polymorphic SSR (simple sequence repeats) markers, seven of which (Satt244, Satt565, Satt038, Satt309, Satt371, Satt570 and Sat_308) were associated with resistance to three main fungal diseases of soybean – frogeye leaf spot, fusarium root rot, and purple seed stain.Results. The average PIC (polymorphism information content) value of the analyzed SSR markers constituted 0.66 ± 0.07, confirming their highlevel polymorphism. The principal coordinate analysis suggested that the local accessions were genetically most close to the accessions from East Asia. As the collection showed a robust resistance to three studied fungal diseases in Almaty Region during 2018–2019, the distribution of the studied SSR markers in the population was not significantly associated with resistance to the analyzed diseases under field conditions.Conclusion. SSR genotyping of the soybean collection helped to identify accessions that potentially possess resistance-associated alleles of fungal disease resistance genes. The data obtained can be further used for the development of DNA documentation and the breeding the promising cultivars and lines of soybean.

Screening of Groundnut (Arachis hypogaea L.) Genotypes for Identification of Sources of Resistance against Leaf Spot Disease

Background: Groundnut (Arachis hypogaea L.) is the fourth most important oil seed crop in the world. The early and late spots are a foliage disease more common and more destructive of groundnut which cause severe yield losses up to 70% and reduces the quality of the pod and fodder. Recent efforts have targeted on developing resistant source against leaf spot disease which are helpful for discarding the hazardous toxic chemical compounds used for controlling the disease. The current study aimed to identify the sources of resistance to leaf spot from the newly identified genotypes as well as from wild species and to study the way in which these were responding to the to the disease development. Methods: Seventy three groundnut genotypes were screened against late leaf spot disease under artificial epiphytotic conditions in field at AICRP on Groundnut, MPKV, Rahuri during kharif 2015-16. The observations of disease intensity and rate of infection were recorded. Result: Among the Seventy three groundnut genotypes, 10 genotypes showed resistant and 33 genotypes showed the moderately resistant reaction to leaf spot disease. The 25 entries showed the susceptible and 05 genotypes showed the highly susceptible reaction to the leaf spot disease. All the susceptible cultivars belong to A. hypogaea sub. sp. fastigiata var. fastigiata to as Spanish bunch. These 10 resistant genotypes of groundnut including two wild species viz., RHRG 6083, KDG 128, GPBD 4, ICGV 94118, ICGV 4983, ICG 12672, ICGV 13160 (A. batizocoi), ICGV 13165 (A. cardenasi), ICG 11426 and ICGV8193 were selected for intensive artificial screening under glasshouse conditions and also confirmed resistance. The resistant lines will be useful to develop introgression lines using marker-assisted backcrossing approach to improve foliar fungal disease resistance in popular groundnut varieties.

Study of Androgenic Plant Families of Alloplasmic Introgression Lines (H. vulgare) –T. aestivum and the Use of Sister DH Lines in Breeding

One of the limitations in obtaining the genetic diversity of doubled haploid (DH) lines via anther culture is the development of families of regenerants, and each family represents a clone. This work examines the results of studying this phenomenon in anther culture of alloplasmic (H. vulgare)–T. aestivum and euplasmic lines with 1RS.1BL and 7DL-7Ai translocations and hybrids between them. Parameters of androgenesis such as the number of embryo-like structures, the total number of regenerants, and the number of green regenerants per 100 anthers varied depending on the genotype. In all genotypes from embryo-like structures, predominant development of families of plantlets rather than single plantlets was found. The source of family plantlets was polyembryos. About 75% of families consisted of regenerants at the same fertility level. On average, 37.74%4% of the R0 plants were fertile. The sister DH lines of three hybrid combinations were formed from seeds of R1 plants (2n = 42) with high fertility and in the presence of wheat–alien translocations. After four years of breeding trials, the sister DH lines of three families with fungal disease resistance increased yield, and some parameters of grain quality exceeding the controls were identified as promising for breeding.