Severe malformation and delayed maturity in peas infected with PSbMV. PSbMV causes similar symptoms in lentils, including stunting, shortening of internodes, reduced leaf size, downward curling of leaflets, chlorosis or necrosis of shoot tips, mild mosaic discoloration of leaves and deformed pods.
Seeds produced by infected plants often are reduced in size. PSbMV-related seed discoloration is less common in lentils than peas. The severity of PSbMV symptoms varies widely. Infected peas and lentils do not always develop symptoms of PSbMV, and infected plants sometimes remain completely asymptomatic, even in susceptible cultivars. Some strains of the virus result in a mild, transient expression of symptoms readily apparent for only a few weeks prior to bloom, while other strains of the virus result in clear symptom expression throughout crop development.
The number of generations of virus transmission exclusively through seed without new transmission events through aphids also can affect symptom expression and result in asymptomatic plants with virus detection only in flowers and seeds. Infected seeds are often asymptomatic, and while infection by PSbMV often results in an overall reduction in seed size and weight, PSbMV-infected seeds can be found in the entire range of seed sizes found in infected seed lots.
PSbMV and other viruses can be difficult to identify accurately on the basis of visual symptoms. Two or more viral diseases often occur together, resulting in a mixture of symptoms. Abiotic stresses such as nutritional imbalances, herbicide toxicity and insufficient or excessive water can result in foliar symptoms similar to those caused by viruses. Seed quality losses caused by PSbMV can easily be confused with damage caused by fungal pathogens or damage incurred during harvest or storage.
Figure 5. Clearing of veins and slight downward curling of leaf margins caused by PSbMV. Figure 6. Deformed pods and malformed terminal rosette caused by PSbMV. Figure 7. Seed discoloration caused by PSbMV. Figure 8. Splitting of seed coats caused by PSbMV. For accurate detection of PSbMV, laboratory analysis is required.
However, when levels of virus infection are low or when virus expression is transient or limited to parts of the plant that were not tested, false negative results still may be reported with these techniques. The evaluation of seed lots for PSbMV is best done with nucleic-acid based or serological techniques.
Bioassays in which seeds are planted in the greenhouse and levels of seed-borne PSbMV are determined by assessing plants for visual symptoms of the virus can result in false-negative results.
Table 1: Percentage of pulse crops infected with pea seed-borne mosaic virus in south eastern Australia, and within crop virus incidence. Support by the Grains Research and Development Corporation is gratefully acknowledged. What to look for PSbMV symptoms on plants are often difficult to identify under field conditions as the virus may be symptomless, or only show mild mosaic symptoms.
Symptoms of PSbMV on pulses are: Field peas develop various degrees of stunting, downward curling of leaflets as well as a transient clearing and swelling of leaf veins in most cultivars. Infected plants may also produce distorted flowers, which often give rise to small distorted pods. Ovule development in affected pods may be uneven, with only one or two seeds being produced. Seed coats may split as the seeds mature. The symptoms on seeds result in brown rings and tan spots. Faba beans develop a systemic dark and light-green leaf mottle, leaf margins become upright and the leaf blade is reduced in size.
The seeds from infected plants show brown ring patterns and reduced size. The distribution of the virus in various parts of the seeds of black gram Vigna mungo L. Hepper plants naturally infected in the field was determined by polymerase chain reaction PCR , Southern blot analysis, and sequencing.
Amaryllis are beautiful, flowering bulbs that are easy to grow and can brighten up your home during the dark days of winter. This article offers some tips for purchasing and caring for them. With the holiday season already underway, garden centers, floral shops and popular retail chains are full of poinsettias. Learn some tips for selecting and caring for them in this article. Caring for Amaryllis From Bulb to Bloom Amaryllis are beautiful, flowering bulbs that are easy to grow and can brighten up your home during the dark days of winter.
Poinsettias: Selecting and Caring for the Most-Popular Holiday Plant With the holiday season already underway, garden centers, floral shops and popular retail chains are full of poinsettias. View the discussion thread.
0コメント