New High Yielding Mung Bean Variety Phule Chetak for Maharashtra

Background: Mung bean is one of the important pulse crop requiring low inputs. The productivity of kharif mung bean is very low. The present improved varieties have lower yield potential and disease susceptibility. There is a need to develop high yielding varieties combined with early to mid synchronous maturity, better quality and resistance/tolerance to major pests and diseases. Methods: The green gram var. Phule Chetak was developed by pedigree selection method from a cross between SML-668 X Naval at Oilseeds Research Station, MPKV, Jalgaon. It was tested over several locations and environments for its stability performance. Result: The results indicated a significant improvement in yield level under field conditions. The new variety Phule Chetak reported an average yield of 1003 kg/ha which is 26.96%, 36.46%, 29.42%, 21.72%, 17.58% and 13.21 per cent higher than the check varieties Vaibhav, BPMR-145, AKM-8802, BM-2002-1, BM-2003-2 and Utkarsha respectively. It is bold seeded having early maturity, moderately resistant to major diseases like powdery mildew, mungbean yellow mosaic virus under field conditions. Considering its consistent performance, the mung bean genotype PM-707-5 has been released for cultivation in the kharif season for Maharashtra under the name of Phule Chetak in Joint Agresco during 29-30 October, 2020 held at Dr PDKV, Akola.

Comprehensive study of selection-value lines of zucchini on the level of damage by the yellow mosaic virus (ZYMV) and manifestation of other diseases

The work is aimed at the selection of linear samples of zucchini (Cucurbita pepo L. var. Giromontia Duch.) with increased complex resistance to abiotic factors of cultivation – zucchini yellow mosaic virus (ZYMV), powdery mildew, bacteriosis and other viral pathogens. Selection studies on choosing virus-resistant zucchini lines from the United Kingdom, Italy, the United States and Spain have identified a number of important correlations levels of resistance to ZYMV and to harmful microorganisms and viruses, belonging to other genera. The assessment of the resistance of the selected zucchini lines to the complex of studied diseases was performed on a 9-point scale of the classifier of the Council for Mutual Economic Assistance (CMEA). In total, during 2017–2019, 20 lines of zucchini were studied in the field. According to the complex resistance to all pathogens (zucchini yellow mosaic virus, green speckled mosaic, white mosaic and cucumber mosaic, bacteriosis and fusarium wilt), four lines have been identified – LZ 17-11, RVL-19, LZ 17-45 and LZ 17-49, which were resistant at the level of points 7 and 9 on the scale of CMEA. The possibility of selecting potentially resistant linear zucchini genotypes for ZYMV based on correlations with the manifestation of other diseases that occurred in the field has been confirmed. The highest level of correlation 0.59<rp<1.0) is observed when comparing the degree of powdery mildew development and symptoms of ZYMV (17 statistically confirmed values of the pairwise correlation coefficient or 80.95 %). A similar indicator for the pair “bacteriosis/ZYMV” is 14 statistically confirmed values of the pairwise correlation coefficient or 66.67 % (–1.0<rp<0.99), and for the pair “field viruses of other origin/ZYMV” – 11 values, which is 52.38 % (–1.0<rp<0.93). Zucchini samples were identified, in which statistically significant correlations were observed for all pairs of comparative traits. Among them, the variety-standard Chaklun and 4 more lines – LZ 17-1, LZ 17-8, LZ 17-50 and LZ 17-44 (–1.0<rp<0.92). The analysis of correlations shows a complex genetic organization of signs of resistance in zucchini lines to the studied pathogens and a high dependence of the manifestation of these signs on the response of the genotype of the line. One of the proofs of this experimental fact is that in all comparative pairs of indicators of the degree of development of certain diseases there are linear genotypes with both positive and negative values of Pearson correlation coefficients (rp). The high level of statistically significant correlations revealed gives grounds for wide use of correlation analysis in selection work for choosing lines potentially resistant to the complex of the most common diseases in vegetable agrocenoses

Targeted Knockout of Eukaryotic Translation Initiation Factor 4E Confers Bymovirus Resistance in Winter Barley

The Eukaryotic Translation Initiation Factor 4E (EIF4E) is a well-known susceptibility factor for potyvirus infections in many plant species. The barley yellow mosaic virus disease, caused by the bymoviruses Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), can lead to yield losses of up to 50% in winter barley. In autumn, the roots of young barley plants are infected by the soil-borne plasmodiophoraceous parasite Polymyxa graminis L. that serves as viral vector. Upon viral establishment and systemic spreading into the upper parts of the plants, yellow mosaics occur as first symptoms on leaves. In the further course of plant development, the disease entails leaf necrosis and increased susceptibility to frost damage. Thanks to the rym4 and rym5 allelic variants of the HvEIF4E gene, more than two thirds of current European winter barley cultivars are resistant to BaYMV and BaMMV. However, several strains of BaYMV and BaMMV have already overcome rym4- and rym5-mediated resistance. Accordingly, new resistance-conferring alleles are needed for barley breeding. Therefore, we performed targeted mutagenesis of the EIF4E gene by Cas9 endonuclease in BaMMV/BaYMV-susceptible winter barley cv. “Igri”. Small insertions were generated, resulting in a shift of the translational reading frame, thereby causing the loss-of-function of EIF4E. The mutations occurred in the homozygous state already in the primary mutants. Their progeny proved invariably homozygous and fully resistant to mechanical inoculation with BaMMV. EIF4E knockout plants showed normal growth habit and produced grains, yet exhibited a yield penalty.

The Melon Zym Locus Conferring Resistance to ZYMV: High Resolution Mapping and Candidate Gene Identification

Zucchini yellow mosaic virus (ZYMV; potyviridae) represents a major pathogen of Cucurbitaceae crops. ZYMV resistance in melon PI 414723 is conditioned by a dominant allele at the Zym locus. This resistant accession restricts viral spread and does not develop mosaic symptoms, but necrosis sometimes develops in response to inoculation. In previous studies, Zym has been mapped to linkage group II of the melon genetic map. In the present study, positional cloning of the locus was undertaken, starting from the CM-AG36 SSR marker at approximately 2 cm distance. We utilized five mapping populations that share the same resistant parent, PI 414723, and analyzed a total of 1630 offspring, to construct a high-resolution genetic map of the Zym locus. Two melon BAC libraries were used for chromosome walking and for developing new markers closer to the resistance gene by BAC-end sequencing. A BAC contig was constructed, and we identified a single BAC clone, from the ZYMV susceptible genotype MR-1, that physically encompasses the resistance gene. A second clone was isolated from another susceptible genotype, WMR 29, and the two clones were fully sequenced and annotated. Additional markers derived from the sequenced region delimited the region to 17.6 kb of a sequence that harbors a NAC-like transcription factor and, depending on the genotype, either two or three R-gene homologs with a CC-NBS-LRR structure. Mapping was confirmed by saturating the map with SNP markers using a single mapping population. The same region was amplified and sequenced also in the ZYMV resistant genotype PI 414723. Because numerous polymorphic sites were noted between genotypes, we could not associate resistance with a specific DNA polymorphism; however, this study enables molecular identification of Zym and paves the way to functional studies of this important locus.

Survey for Yellow Mosaic Disease Occurring on Blackgram [Vigna mungo (L.) Hepper] and Weed Hosts in Four Major Blackgram Growing Districts of Andhra Pradesh and Characterization of Associated Viruses using Coat Protein Gene

Background: Yellow mosaic disease (YMD) caused by Yellow mosaic virus is one of the major constraints in the pulse production in Andhra Pradesh (A.P.) due to fast evolution of strains, like Mungbean yellow mosaic India virus (MYMIV). Keeping this in view, a survey was undertaken in the major blackgram growing districts of A.P. to know the YMD incidence in blackgram and weed hosts and were characterized based on genetic features by comparing with other YMV isolates from different hosts and locations across the world. Methods: Roving survey was conducted during rabi 2019-20 in major blackgram growing districts of A.P. viz., Krishna, Guntur, West Godavari and Prakasam districts for YMD incidence. Blackgram plants showing characteristic symptoms were collected as representative samples from each mandal along with the suspected weed plants and were subjected to amplification using coat protein (CP) specific primers followed by molecular characterization. Phylogenetic tree for coat protein (CP) gene was constructed using aligned sequences with 1000 bootstrap replicates following neighbor-joining phylogeny. Result: Out of the four districts surveyed, the highest disease incidence was recorded at Machavaram village of Prakasam district (43.22%), whereas least disease incidence was recorded at Chinaganjam village of Praksam district (2.4%). Six weeds viz., Ageratum conyzoides, Amaranthus viridis, Parthenium hysterophporus, Vigna trilobata, Abelmoscus moschatus, Desmodium laxiflorum have showed positive result in PCR amplification with MYMIV specific coat protein primers. Four isolates from blackgram samples and two from weed plants shared 94.85 to 99.58% nucleotide identity among themselves.