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.

Molecular Cloning of MYMV Genome and Infectivity of Yellow Mosaic Virus in Green Gram Using Different Viral Transmission Tools

Mungbean yellow mosaic virus (MYMV) causes massive crop losses in green gram. MYMV is a member of begomovirus with bipartite genome comprising DNA-A and DNA-B components, which is transmitted by whiteflies. Cloning and preparation of infectious clone is very much essential for screening germplasm or transgenic material of pulse crops since viruliferous whiteflies may not be available throughout the year. In the current work, we have amplified rolling circle mediated viral genome of MYMV using Φ29 DNA polymerase. The amplified products was digested and cloned into the plant expression vector pCAMBIA2301.The cloned constructs was then transformed into Agrobacterium LBA4404 through freeze thaw method. Further, three viral transmission techniques including mechanical rubbing, Agroinfiltration and Agroinoculation, were employed for assessing the mosaic symptoms in green gram. The molecular confirmation through polymerase chain reaction (PCR) indicated that the yellow mosaic symptoms were formed due to infectivity of MYMV in the green gram.

Salicylic Acid Induced Resistance against Mungbean Yellow Mosaic Virus (MYMV) and Enhanced Seed Yield in Resistant and Susceptible Urdbean [Vigna mungo (L.) Heper] Genotypes

Background: Urdbean’s low productivity is largely due to its susceptibility against whitefly-transmitted mungbean yellow mosaic virus (MYMV) disease. The effect of Salicylic acid (SA) on MYMV disease resistance and its impact on seed yield under field conditions on diverse genotypes is largely unknown. Therefore, in present investigation, we have analysed the effect of SA on induction of antioxidant enzymes leading to MYMV resistance and enhanced seed yield in urdbean genotypes. Methods: Different concentrations of SA were sprayed on 3 week-old susceptible urdbean genotype (LBG 623) and induction of antioxidant enzymes was analysed. A pot experiment was conducted to see the effect of SA on initial induction of antioxidant enzymes maintained over long period of time in 39 urdbean genotypes. Under field conditions, the effect of SA treatment on MYMV disease resistance and seed yield was assessed. Result: Rise in antioxidant enzyme production was observed in SA treated urdbean plants challenged with MYMV. The field experiment revealed that exogenous SA application significantly reduced MYMV incidence and increased seed yield in all 39 urdbean genotypes tested. The ability to confer MYMV resistance along with the increase in seed yield suggests the incorporation of SA in effective MYMV management strategies in urdbean.

The impact of insecticides and plant extracts on the suppression of insect vector (Bemisia tabaci) of Mungbean yellow mosaic virus (MYMV)

Mungbean yellow mosaic virus (MYMV) is an important constraint in successful production of mungbean (Vigna radiata L.) in many countries, including Pakistan. The MYMV spreads by insect vector whitefly (Bemisia tabaci Gennadius). The use of resistant cultivars is the most effective management tactics for MYMV. Twenty mungbean varieties/lines were screened against insect vector of MYMV under field condition in the current study. Resistance levels for varieties/lines were assessed through visual scoring of typical disease symptoms. Furthermore, the impacts of two insecticides ‘Imidacloprid’ and ‘Thiamethoxam’ and two plant extracts, i.e., neem (Azadirachta indica), and Eucalyptus (Eucalyptus camaldulensis) were tested on the suppression of whitefly. Field screening indicated that none of the tested varieties/lines proved immune/highly resistant, while significant variations were recorded among varieties/lines for resistance level. All varieties/lines were systemically infected with MYMV. The varieties ‘AARI-2006’ and ‘Mung-14043’ were considered as resistant to MYMV based on visual symptoms and the lowest vector population. These varieties were followed by ‘NM-2006’ and ‘NL-31’, which proved as moderately resistant to MYMV. All remaining varieties/lines were grouped as moderately to highly susceptible to MYMV based on visual symptoms’ scoring. These results revealed that existing mungbean germplasm do not possess high resistance level MYMV. However, the lines showing higher resistance in the current study must be exploited in breeding programs for the development of resistant mungbean varieties/lines against MYMV. Imidacloprid proved as the most effective insecticide at all concentrations to manage whitefly population. Therefore, use of the varieties with higher resistance level and spraying Imidacloprid could lower the incidence of MYMV.

​RCA-based Detection of Begomoviruses in Weed Ggenera Associated with Legumes in Southern Karnataka

Background: Yellow mosaic disease (YMD) caused by begomoviruses transmitted through the insect vector Bemisia tabaci poses a serious threat to the production of legume crops. Methods: Season-long surveys were carried out for YMD occurrence in six different legume crops and associated natural weeds both symptomatic and asymptomatic across the districts of southern Karnataka, India. The samples were analyzed through RCA PCR using specific primer pairs. Result: Up to 94.1 per cent YMD incidence was recorded and nine weed species were commonly found associated with legume crops. The weeds viz., Ageratum conyzoides, Alternanthera sessilis, Commelina benghalensis and Euphorbia geniculata were abundantly found in the surveyed regions. The weeds were both symptomatic and asymptomatic. Rolling circle amplification coupled polymerase chain reaction method was employed to detect yellow mosaic virus in asymptomatic weeds. Phylogenetic analysis based on the sequences of PCR amplified products of weeds and symptomatic legumes revealed a close clustering of the weed samples with horsegram yellow mosaic virus, legume yellow mosaic virus and mungbean yellow mosaic virus. Overall, our data suggests the role of weed species associated with legume crops as alternative/collateral hosts of begomoviruses and their role in the epidemiology of yellow mosaic disease.

​RCA-based Detection of Begomoviruses in Weed Genera Associated with Legumes in Southern Karnataka

Background: Yellow mosaic disease (YMD) caused by begomoviruses transmitted through the insect vector Bemisia tabaci poses a serious threat to the production of legume crops. Methods: Season-long surveys were carried out for YMD occurrence in six different legume crops and associated natural weeds both symptomatic and asymptomatic across the districts of southern Karnataka, India. The samples were analyzed through RCA PCR using specific primer pairs. Result: Up to 94.1 per cent YMD incidence was recorded and nine weed species were commonly found associated with legume crops. The weeds viz., Ageratum conyzoides, Alternanthera sessilis, Commelina benghalensis and Euphorbia geniculata were abundantly found in the surveyed regions. The weeds were both symptomatic and asymptomatic. Rolling circle amplification coupled polymerase chain reaction method was employed to detect yellow mosaic virus in asymptomatic weeds. Phylogenetic analysis based on the sequences of PCR amplified products of weeds and symptomatic legumes revealed a close clustering of the weed samples with horsegram yellow mosaic virus, legume yellow mosaic virus and mungbean yellow mosaic virus. Overall, our data suggests the role of weed species associated with legume crops as alternative/collateral hosts of begomoviruses and their role in the epidemiology of yellow mosaic disease.

Inheritance Pattern of Mungbean Yellow Mosaic Virus (MYMV) Disease Resistance in Blackgram [Vigna mungo (L.) Hepper]

Background: Mungbean yellow mosaic virus (MYMV) disease is the most destructive disease in blackgram. Development of MYMV resistant varieties is one of the best possible solutions to avoid the yield reduction in blackgram. There are conflicting reports on the genetics of resistance to MYMV disease claiming that it is controlled by both dominant and recessive genes. Hence the present study was aimed to understand the inheritance pattern of the MYMV disease resistance in eight crosses of blackgram.Methods: Parents, F1 and F2 generation of eight cross combinations were raised during July - Sep, 2018 at National Pulses Research Centre, Tamil Nadu Agricultural University, Vamban, Tamil Nadu. An infector row of CO 5 was raised to intensify the MYMV disease pressure after every eight rows. Based on disease incidence on 60th day after sowing, two phenotypic classes were formed among F2 plants with the scales of (1 to 3) as resistant phenotype and (4 to 9) as susceptible phenotype. The goodness of fit to Mendelian segregation ratio for MYMV disease resistance in the segregating population was tested by Chi square test (Stansfield, 1991).Result: The MYMV disease incidence was tri-genically controlled with inhibitory gene action in four crosses viz., MDU 1 x Mash 114, CO5 x Mash 114, MDU 1 x VBN 6 and CO 5 x VBN 6. Complementary gene action with two genes was observed in four crosses viz., MDU 1 x Mash 1008, CO 5 x Mash 1008, MDU 1 x VBN 8 and CO 5 x VBN 8. Differences in number of genes were observed due to the presence of recessive inhibitory gene in both male and female parents of the crosses which had complementary gene action for MYMV disease. The putative gene symbols assigned for the six genotypes viz., S1S1S2S2ii (MDU 1 and CO 5), s1s1s2s2II (Mash 114 and VBN 6) and s1s1s2s2ii (Mash 1008 and VBN 8), respectively.