Temperature Affects Expression of Symptoms Induced by Soybean Mosaic Virus in Homozygous and Heterozygous Plants.

Dexiao Li; Pengyin Chen; Ainong Shi; Shakiba, Ehsan; Gergerich, Rose; Yaofeng Chen

Seven strains (G1 to G7) of soybean mosaic virus (SMV) and 3 resistance loci (Rsv1, Rsv1, and Rsv4) have been identified in soybean. The interaction of SMV strains and host resistance genes results in resistant (symptomless), susceptible (mosaic), or necrotic (leaf and stem necrosis) reactions. The necrotic reaction may be gene dosage dependent and influenced by temperature. Using a set of soybean isolines and hybrids containing homozygous or heterozygous alleles of rsv, Rsv1, Rsv1-n, Rsv3, or Rsv4, this study has explored the relationship of SMV-induced symptoms and resistance gene dosage at different temperatures. Results showed that SMV-inoculared plants carrying Rsv1 or Rst4 were symptomless at both homozygous and heterozygous states at all temperature regimes. Threshold temperatures for symptoms changing from stem tip necrosis (STN) to mosaic were 30, 33, and 33 °C in G7-inoculated homozygous genotypes V94-3971 (Rsv1) and PI 96983 (Rsv1) and G1-inoculated V262 (Rsv1-n), respectively. However, at the heterozygous state, threshold temperature was 30 °C in G7-inoculated V94-3971 x Essex F[sub1] for the symptom change from STN to mosaic, 31 °C in G7-inoculated Essex x PI 96983 F[sub1] from STN to mixture of necrosis and mosaic (N-M), and 32 °C in Gi-inoculated \T262 x Essex F1 from N-M to mosaic. Incomplete necrosis was observed in the heterozygous state in G1-inoculated V262 x Essex F[sub1] and G7-inoculated PT 96983 x Essex F[sub1] where necrotic and mosaic symptoms were mixed. High temperature (37 °C) tends to mask the expression of mosaic symptoms in both homozygous and heterozygous plants. STN expression in response to temperature was affected by resistance gene, gene dosage, host genetic background, and specific SMV strains. Thus, Rsv3 and Rsv4 are a better choice as source of genetic resistance for breeding SMV-resistant cultivars.

CROP genetics; SOYBEAN; SOYBEAN mosaic virus; EFFECT of temperature on plants; GENETICS of disease resistance of plants; NECROSIS; HETEROZYGOSITY; GENETIC research; PLANT genetics

Journal of Heredity, 2009, Vol 100, Issue 3, p348

0022-1503

Academic Journal

10.1093/jhered/esn109