The absence of seed lectin in common bean (Phaseolus vulgaris L.) was shown to be inherited as a single recessive gene and allelic to genes conditioning 6 different lectin types. In inbred backcross lines, the allele from ‘Sanilac’ (a navy class bean) for the presence of lectin was semidominant to the lectinless allele from ‘U.I. 1140’ (a Great Northern class bean) for quantity of lectin. Backcross lines with lectin (L/L) and without lectin (1/1) were developed using 2 lectinless donor parents (‘U.I. 1140’ and ‘U.I. 111', a Pinto class bean) and ‘Sanilac’ as the recurrent parent. Backcross lines and parents were grown in the field and analyzed for days to flower, seed yield, seed weight, percentage protein, and quantities of lectin and phaseolin. There were significant differences between lectin genotypes (L/L vs. 1/1) for all traits except yield, seed weight, and nonphaseolin nonlectin protein. Backcross lines without lectin had substantially higher levels of phaseolin and slightly more total protein than lines with lectin. The data suggested that phaseolin over-compensated for the absence of lectin in 1/1 backcross lines. The implications of these findings toward the nutritional improvement of bean protein are discussed.
Leaving an extra plant in the space adjacent to a missing plant at the time of thinning provided better compensation for missing plants within plots of bean (Phaseolus vulgaris L.) with respect to seed yield and percentage protein than transplanting seedlings grown from remnant seed.
Field and greenhouse experiments were conducted to study the relationships among plant growth traits; ratios of dry weights among nodules, roots, and shoots; and traits associated with N2-fixation potential of common bean (Phaseolus vulgaris L.). The dry weights of plant parts and the traits associated with N2-fixation differed among the 10 lines studied. A visual nodulation score used to evaluate N2-fixation potential was correlated positively with nodule dry weight, acetylene reduction (AR) value, root dry weight, and shoot dry weight for plants grown under both greenhouse and field conditions. AR values, nodule dry weight, and visual nodule scores of plants grown in the greenhouse were correlated positively with the respective figures obtained for field-grown plants. These methods of evaluation can be used to discriminate among lines for N2-fixation potential.
HortScience will undergo some changes that the Publications Committee and the publications staff believe will increase interest and expand usefulness of this publication. The first of these changes—the reorganization of the currently combined Reports & Notes section into 2 separate sections—will begin with the Feb. 1985 issue.
Screening of 107 bean cultivars and plant introductions (PI) by 2-dimensional electrophoresis revealed only 3 different phaseolin patterns: Tendergreen (T), Sanilac (S), and Contender (C). The majority of the lines had either the ‘T’ (25%) or ‘S’ (69%) phaseolin patterns, with only 6% having the ‘C’ pattern. Phaseolin pattern was not strictly associated with commercial class but most cultivars with the ‘T’ pattern were snap beans, while the majority of lines with the ‘S’ pattern were dry beans. Furthermore, the phaseolin types of 15 cultivars were associated with previous cultivar groupings that were based on calculations of genetic relationships. A genetic distinction was noted between the groups of cultivars containing the ‘T’ and ‘S’ phaseolin patterns.
Candidate gene (CG) analysis can be an efficient approach for identifying genes controlling important traits in fruit production. Three chronological steps have been described for determining candidate genes for a trait—proposing, screening, and validating—and we have applied these to the problem of internal breakdown of peach and nectarine. Internal breakdown (IB), also known as chilling injury, is the collective term for various disorders that occur during prolonged cold storage and/or after subsequent ripening of stone fruit. Symptoms include mealiness, browning, and bleeding. Candidate genes for IB symptoms were proposed based on knowledge of the biochemical or physiological pathways leading to phenotypic expression of the traits. Gene sequences for proposed CGs were obtained primarily from the Genome Database for Rosaceae. Screening the CGs involved identifying polymorphism within a progeny population, relying mainly on simple PCR tests. Several polymorphic CGs were located on a peach linkage map and compared with phenotypic variation for IB susceptibility. A major QTL for mealiness coincided with the Freestone-Melting flesh locus, which itself is likely to be controlled by a CG encoding endopolygalacturonase, an enzyme involved in pectin degradation. Further gene sequences positioned on the consensus linkage map of Prunus by other researchers were co-located with QTLs for IB traits. Validation of the role of identified CGs will require detailed physiological or transgenic studies.