Following deliberations were made during the meeting.
1. Tropical countries have more viruses. The host range of the begomovirus is increasing. Most of the begomoviruses are recombinant. Recombination is not happening in cotton virus but in viruses infecting other host plants (weeds, ornamental plants). A new strain of CLCuBV is identified with distinct recombination sites. Virus didn’t change since 2001, but now recombination is found again which could lead to evolution of new species.
Cotton is infected only with Cotton leaf curl Multan betasatellite (CLCuMB), and Chilli leaf curl betasatellite (ChLCB). Chinese CLCuMB isolates are different from rest of the betasatellites.
High alphasatellite concentration suppress the concentration of betasatellite and vice versa. Alphasatellites were not amplified from all the plants infected with begomoviruses. Cotton infecting alphasatellites include Cotton leaf curl Multan alphasatellite (CLCuMA) and Okra leaf curl alphasatellite (OLCA). Multiple alphasatellite are isolated from a single plant of cotton (grown in sentinel plants). These alphasatellite including Gossypium darwinii symptomless alphasatellite (GDarSLA), Cotton leaf curl Burewala alphasatellite (CLCuBuA), and Okra leaf curl alphasatellite (OLCA). Alphasatellite are also reported from sweet potato. qPCR shows that G. arboreum is a host of begomovirus but with extreme resistance. The two methods of sampling (sentinel plot and field sampling) appear to be giving the same range of viruses
Plant infected with Mastrevirus (CpCDV) included Cucumber, Cotton (G. arborium ), Okra and Tomatos. C strain of CpCDV from vegetables and L strain from Cotton was found
2. Cotton leaf curl Burewala virus (CLCuBuV) is dominating (99%) in the region both in sentinel as well as in field conditions. Other cotton infecting begomovirus includes Mesta yellow vein mosaic virus (MeYVMV), Tomato leaf curl New Delhi virus (ToLCNDV). Cotton leaf curl complex is possibly changing with reference to virus but not betasatellite. We know little about alphasatellite. The hypothesis regarding grouping of Chili leaf curl betasatellites on the basis of North and South regions is possibly no longer valid.
3. Due to diverse environment virus is changing in Punjab
4. Results of qPCR are surprising. Mac7, which is resistant variety, shows low quantity (in picogram) of alphasatellite. Since Alpha is self-replicating, it should be high in quantity but it is not. Only minute quantity is observed in qPCR.
Quantitation of virus/satellites in different cotton samples of different disease rating scales (from stage 1 – 4) varies. Alpha and virus concentration is almost same but betasatellite behave differently. Stage four has less concentration compare to stage 3. At stage 1 more virus but at stages 2 -3 it is not. So It may concluded that there is no direct relationship between virus load and symptoms severity. Likely varietal susceptibility also plays a part.
5. In whitefly, all haplotypes are members of Asian clade. Some geographical clustering also occurs. Two types of whiteflies were reported from whole Punjab province and along the main trunk road of Sindh province. But the situation in deep Sindh province is different. There exist more diversity of whitefly (five biotypes) and Asian II-I is dominating in Punjab province (approx. 74%) followed by Asian I (9%) and MEAM (15%) in Sindh province.
There is need to collect more sample to draw the actual picture. Virus in Sindh province is different compare to virus in Punjab province this might be because of the difference in whiteflies in Sindh and Punjab provinces.
6. The matter of combined publication remains unresolved.
7. Approx. 140 papers are included in the Cotton Compendium. The papers and contribution will be circulated to all partners.
8. The contents of the CLCuD virology book/booklet will be decided first, followed by the selection of the Editor which will most probably be Judith K. Brown. After decision on the contents of the booklets, virology group members will write chapters as assigned by the editor.