Mitoviruses have small RNA(+) genomes, replicate in mitochondria, and have been shown to infect only fungi to date. For this report, sequences that appear to represent nearly complete plant mitovirus genomes were recovered from publicly available transcriptome data. Twenty of the refined sequences, 2684-2898 nt long and derived from 10 different species of land plants, appear to encompass the complete coding regions of contemporary plant mitoviruses, which furthermore constitute a monophyletic cluster within genus Mitovirus. Complete coding sequences of several of these viruses were recovered from multiple transcriptome (but not genome) studies of the same plant species and also from multiple plant tissues. Crop plants among implicated hosts include beet and hemp. Other new results suggest that such genuine plant mitoviruses were immediate ancestors to endogenized mitovirus elements now widespread in land plant genomes. Whether these mitoviruses are wholly cryptic with regard to plant health remains to be investigated.

Floral nectar and other reward facilitate crop pollination, and in so doing, increase the amount and breadth of food available for humans. Though abundance and diversity of pollinators (particularly bees) have declined over the past several decades, a concomitant increase in reliance on pollinators presents a challenge to food production. Development of crop varieties with specific nectar or nectar-related traits to attract and retain pollinating insects is an appealing strategy to help address needs of agriculture and pollinators for several reasons. First, many crops have specific traits which have been identified to enhance crop–pollinator interactions. Also, an improved understanding of mechanisms that govern nectar-related traits suggest simplified phenotyping and breeding are possible. Finally, the use of nectar-related traits to enhance crop pollination should complement other measures promoting pollinators and will not limit options for crop production or require any changes by growers (other than planting varieties that are more attractive or rewarding to pollinators). In this article, we review the rationale for improving crop-pollinator interactions, the effects of specific plant traits on pollinator species, and use cultivated sunflowers as a case study. Recent research in sunflower has (i) associated variation in bee visitation with specific floral traits, (ii) quantified benefits of pollinators to hybrid yields, and (iii) used genetic resources in sunflower and other plants to find markers associated with key floral traits. Forthcoming work to increase pollinator rewards should enable sunflower to act as a model for using nectar-related traits to enhance crop–pollinator interactions.

Storage temperature affects the rate and extent of wound-healing in a number of root and tuber crops. The effect of storage temperature on wound-healing in sugarbeet (Beta vulgaris L.) roots, however, is largely unknown. Wound-healing of sugarbeet roots was investigated using surface-abraded roots stored at 6 and 12°C for 28 days. Surface abrasions are common injuries of stored roots, and the storage temperatures used are typical of freshly harvested or rapidly cooled roots. Transpiration rate from the wounded surface and root weight loss were used to quantify wound healing. At 12°C, transpiration rate from the wounded surface declined within 14 days and wounded roots lost weight at a rate similar to unwounded controls. At 6°C, transpiration rate from the wounded surface did not decline in the 28 days after injury, and wounded roots lost 44% more weight than controls after 28 days storage. Melanin formation, lignification, and suberization occurred more rapidly at 12°C than at 6°C, and a continuous layer of lignified and suberized cells developed at 12°C, but not at 6°C. Examination of enzyme activities involved in melanin, lignin, and suberin formation indicated that differences in melanin formation at 6 and 12°C were related to differences in polyphenol oxidase activity, although no relationships between suberin or lignin formation and phenylalanine ammonia lyase or peroxidase activity were evident. Wound-induced respiration was initially greater at 12°C than at 6°C. However, with continued storage, respiration rate of wounded roots declined more rapidly at 12°C, and over 28 days, the increase in respiration due to injury was 52% greater in roots stored at 6°C than in roots stored at 12°C. The data indicate that storage at 6°C severely slowed and impaired wound-healing of surface-abraded sugarbeet roots relative to roots stored at 12°C and suggest that postharvest losses may be accelerated if freshly harvested roots are cooled too quickly.